The current methods for the manufacture of toothed abrasive tools (Technology of machining and assembly in precision machine building. I976 "Mashinostroyeniye", Moscow, p. 210-214) consist in hot or cold moulding of an abrasive mass with a bond in a special metal or plastic press mould serving as a tool counterform. However, the need for special complicated dies, particularly for the abrasive tools in the form of a bevel gear wheel with circular teeth raises considerably the amount of labour and expenditures for their manufacture thus hampering wide introduction into industry of finish-machining of bevel gears with such tools. Besides, the abrasive tool moulded in this way calls for subsequent finishing of teeth with diamond tools to improve conjugation of the tool teeth with the teeth of the work, to increase accuracy and open the cutting drains.
There is another known method for the manufacture of toothed abrasive tools (SU, A, 356112). According to this method the diamond shaver in the form of a gear wheel is machined with a similar shaver having a considerably larger number of teeth by mutual generation in engagement and by forced rotation of both tools at a preset speed ratio. In the course of generation the contact zone of their teeth is fed with free abrasive. This method is used predominantly for dressing already manufactured toothed tools and cannot be used for moulding a toothed abrasive tool from a whole blank. Besides, the dressing tool and the tool being dressed have too meet stringent demands regarding the characteristic and amount of abrasive which limits the application of this method.
The method for making, shaped abrasive tools (DE, A 1. 3314453) approaches most closely the one disclosed herein. In this method machining is done with a profile tool of the shape contrary to that of the abrasive tool being machined. The machining tool is set with relation to the work being profiled with a certain clearance into which free abrasive is fed. The profiling tool rotates the work being profiled by means of the grains of free abrasive located between the two. Such kinematics of mutual rotation results in inevitable slipping of the abrasive work being profilled relative to the profiling tool. For this reason this method is suitable for shaping the working surfaces whose generatrix is parallel to the generatrix of the blank or is set at a small angle thereto as is the case when dressing worm abrasive wheels for grinding spur gear wheels. (N. P. Sobolev et al. Tooth-machining machines and tools and instrument building industry, I963, "Mashgiz", Moscow-Leningrad, p. 239). The manufacture of abrasive tool in the form of a bevel gear wheel with circular teeth, i.e. a hone, is impossible in this method because the generatrix of the tooth being shaped is set at a large angle to the generating surface on which the gear rim is shaped. Therefore, when the free abrasive grains roll over the surface of the abrasive blank the way the balls roll in the ball bearing, the teeth being shaped on said blank are inevitable bound to be cut off.
In another method for finish-machining of gear wheels (SU, A, 199643) each of the mating gear wheels of the working pair is machined with a toothed tool of its own, whose cutting edges are arranged over the surface determined with the provision that the wheel being machined meshes with the machining wheel, the later being set with a hypoid offset with relation to the wheel being machined. In view of the fact that mating of the machining surface of the tooth with the surface being machined is achieved by approximate methods, the existing methods of tooth forming, e.g. on metal-working equipment produce the working surface of the tool tooth which only approaches the complete mating with the surface of the tooth of the wheel being machined. Therefore, such a tool does not have the requisite accuracy characteristics permitting various kinds of gear wheels to be machined with a high precision. Besides, separate manufacture of abrasive tools and separate machining therewith of each of the mating wheels in a pair reduces the efficiency of both tool manufacture and finish machining.